Effects of Isochoric Freezing Conditions on Cut Potato Quality

Isochoric freezing is a pressure freezing technique that could be used to retain the beneficial effects of food storage at temperatures below their freezing point without ice damage. In this study, potato cylinders were frozen in an isochoric system and examined using full factorial combinations of three processing procedures (immersed in water, vacuum-packed and immersed in ascorbic acid solution), four freezing temperatures/pressures (−3 °C/37 MPa, −6 °C/71 MPa, −9 °C/101 MPa and −15 °C/156 MPa) and two average compression rates (less than 0.02 and more than 0.16 MPa/s). The effects of process variables on critical quality attributes of frozen potatoes after thawing were investigated, including mass change, volume change, water holding capacity, color and texture. Processing procedure and freezing temperature/pressure were found to be highly significant factors, whereas the significance of the compression rate was lower. For the processing procedures, immersion in an isotonic solution of 5% ascorbic acid best preserved quality attributes. At the highest pressure level of 156 MPa and low compression rate of 0.02 MPa/s, potato samples immersed in ascorbic acid retained their color, 98.5% mass and 84% elasticity modulus value. These samples also showed a 1% increase in volume and 13% increase in maximum stress due to pressure-induced hardening.

Potato Market and Consumption

Potato, or as it is called the “bread of the poor”, is a traditional product and the fourth world's largest consumption culture after rice, wheat, and maize. Potato contains vitamin B6 (32%), starch (26%), copper (22%), vitamin C (22%), magnesium (19%), phosphorus (17%), fiber (15%), pantothenic acid (13%), and other ingredients. Americans eat on average 35 kg of frozen potatoes per year: 19 kg of fresh potatoes; 8 kg of potato chips; and 6 kg of dehydrated potato products. The global monthly consumption of potato per capita is 31.3 kg. A greater consumption per capita is in Europe with 87.8 kg/capita. Residents of cold countries of Eastern Europe are the biggest consumers of potatoes in the world. China is the largest producer in the world (75mil / year), but it is not the largest consumer per capita. The volume of international potato trade is smaller than the volume of production. Only 6% of potato production reaches trade market worldwide. Trade in processed potatoes is increased, and with higher rates exceed fresh potato trade. It passes from fresh consumption to processed consumption. Developed countries are those which provide markets with these processed products, earning high rate of profits. Processed potatoes make up 64 percent of total US potato consuming. Kosovo has a great potential to produce potatoes, but there are some obstacles such as small domestic consumption and the market in general. In this article, the factors that affect consumption are explored, which as a consequence increase the production.